Citations

Abstract Fetal-derived tissue-resident macrophages exhibit stem cell-like features of self-renewal in adulthood to maintain macrophage population during homeostasis and/or various insults. However, little is known about the cellular and molecular mechanisms modulating proliferative and inflammatory fate decisions of tissue-resident macrophages in vivo. Here, we show that WNT-β-catenin signaling inhibited lung-resident alveolar macrophage (AM) self-renewal, while simultaneously promoted AM inflammatory activities in vitro and in vivo during influenza virus infection. Mechanistically, WNT engagement facilitated the binding of β-catenin with HIF-1α over its conventional binding partner TCF-4. Such a binding choice led to the elevated macrophage inflammation in a glycolysis-dependent manner, while inhibited AM self-renewal by causing mitochondrial damage and impairing oxidative phosphorylation. Thus, AM self-renewal and inflammatory activity are uncoupled by WNT-β-catenin signaling through HIF-1α-mediated cellular metabolic choice. Importantly, we showed that AM with high HIF-1α activity had limited proliferative capacity and produced inflammatory cytokines, while AM with low HIF-1α activity were highly proliferative and expressed genes associated with tissue repair function in vivo during influenza virus infection. In accordance, we demonstrated that AM proliferation and repopulation were needed for optimal lung repair following the clearance of influenza virus in the respiratory tract. Our results have revealed key mechanisms modulating macrophage fate choice between progeny production versus inflammatory effector activity, and subsequent effects on tissue inflammation and repair.

Abstract Tissue-resident memory CD8+ T cells (TRM) share characteristics and core residency gene programs with tumor-infiltrating lymphocytes (TILs). However, the transcriptional, metabolic and epigenetic regulation of TRM and TIL differentiation, maintenance and function are largely undefined. Furthermore, it is unknown whether metabolic and epigenetic manipulations can be employed to promote TRM/TIL functional programs for cancer immunotherapy. Here we report a critical mechanism programming the mitochondrial and epigenetic regulation of TRM/TIL functionality in situ. We find that mouse and human TRM/TIL express the transcription factor BHLHE40 and the BHLHE40-associated gene signature. Bhlhe40 is specifically required for TRM and TIL development and poly-functionality. Local PD-1 signaling inhibits TIL Bhlhe40 expression, and Bhlhe40 is critical for TIL reinvigoration following anti-PD therapy. Mechanistically, Bhlhe40 sustains TRM/TIL mitochondrial fitness for the promotion of a functional epigenetic state. Building on these findings, we also identify an epigenetic and metabolic regimen that promotes TRM/TIL gene signatures associated with tissue residency and poly-functionality through in vitro T cell screening. Strikingly, this regimen empowers the anti-tumor activity of CD8+ T cells and possesses therapeutic potential even at an advanced tumor stage in mouse models. Our results provide mechanistic insights on the local regulation of TRM and TIL function, and offer a viable strategy for developing novel immunotherapeutic means for cancer.

SARS-CoV-2 mRNA vaccination induces robust humoral and cellular immunity in the circulation; however, it is currently unknown whether it elicits effective immune responses in the respiratory tract, particularly against variants of concern (VOCs), including Omicron. We compared the SARS-CoV-2 S–specific total and neutralizing antibody responses, and B and T cell immunity, in the bronchoalveolar lavage fluid (BAL) and blood of COVID-19–vaccinated individuals and hospitalized patients. Vaccinated individuals had significantly lower levels of neutralizing antibody against D614G, Delta (B.1.617.2), and Omicron BA.1.1 in the BAL compared with COVID-19 convalescents despite robust S-specific antibody responses in the blood. Furthermore, mRNA vaccination induced circulating S-specific B and T cell immunity, but in contrast to COVID-19 convalescents, these responses were absent in the BAL of vaccinated individuals. Using a mouse immunization model, we demonstrated that systemic mRNA vaccination alone induced weak respiratory mucosal neutralizing antibody responses, especially against SARS-CoV-2 Omicron BA.1.1 in mice; however, a combination of systemic mRNA vaccination plus mucosal adenovirus-S immunization induced strong neutralizing antibody responses not only against the ancestral virus but also the Omicron BA.1.1 variant. Together, our study supports the contention that the current COVID-19 vaccines are highly effective against severe disease development, likely through recruiting circulating B and T cell responses during reinfection, but offer limited protection against breakthrough infection, especially by the Omicron sublineage. Hence, mucosal booster vaccination is needed to establish robust sterilizing immunity in the respiratory tract against SARS-CoV-2, including infection by the Omicron sublineage and future VOCs.

Abstract Alveolar macrophages (AMs) are major lung tissue-resident macrophages capable of proliferating and self-renewal in situ. AMs are vital in pulmonary antimicrobial immunity and surfactant clearance. The mechanisms regulating AM compartment formation and maintenance remain to be fully elucidated currently. In this study, we have explored the roles of mitochondrial transcription factor A (TFAM)–mediated mitochondrial fitness and metabolism in regulating AM formation and function. We found that TFAM deficiency in mice resulted in significantly reduced AM numbers and impaired AM maturation in vivo. TFAM deficiency was not required for the generation of AM precursors nor the differentiation of AM precursors into AMs, but was critical for the maintenance of AM compartment. Mechanistically, TFAM deficiency diminished gene programs associated with AM proliferation and self-renewal and promoted the expression of inflammatory genes in AMs. We further showed that TFAM-mediated AM compartment impairment resulted in defective clearance of cellular debris and surfactant in the lung and increased the host susceptibility to severe influenza virus infection. Finally, we found that influenza virus infection in AMs led to impaired TFAM expression and diminished mitochondrial fitness and metabolism. Thus, our data have established the critical function of TFAM-mediated mitochondrial metabolism in AM maintenance and function.

Respiratory tissue resident–like CD8 + T cells are associated with chronic lung sequelae post-acute COVID-19.

Identification of a CD4 + helper T cell population providing in situ help to B and CD8 + T cells in the respiratory mucosa.

Age-associated T RM cell malfunction supports chronic lung inflammation and tissue fibrosis after respiratory viral infection.

7030 Background: JAK2V617F occurs in approximately 50% of patients with essential thrombocythemia. Qualitative studies of mutation analysis have previously reported an association between JAK2V617F and advanced age, higher hemoglobin level, higher leukocyte count, and lower platelet count. A possible association with thrombotic complication has also been considered. Methods: Allele-specific, quantitative PCR analysis for JAK2V617F was performed on 176 patients with ET, using genomic DNA from archived bone marrow, which was collected within one year (n=72), between 1 and 5 years (n=64), or after 5 years (n=40) of diagnosis. Results: JAK2V617F was detected in 96 patients (55%), in whom mutant allele burden ranged from 1% to 100% (median 6.3%). Neither mutational frequency (p=0.37) nor mutant allele burden (p=0.62) was affected by the timing of bone marrow sample collection. Presence of JAK2V617F was significantly associated with higher hemoglobin level (p<0.0001), lower platelet count (p=0.001), higher leukocyte count (p=0.008), increased incidence of venous thrombosis occurring after diagnosis (p=0.02), and older age at diagnosis (p=0.03). All but age retained significance in multivariable analysis. In mutation-positive patients (n=96), JAK2V617F allele burden clustered between 1% and 22% in 94 cases, in whom it correlated directly and significantly with platelet and leukocyte counts, palpable splenomegaly at diagnosis, and venous thrombosis occurring after diagnosis. Conclusions: JAK2V617F allele burden imparts additional phenotypic effects in ET. No significant financial relationships to disclose.